Variable displacement pump

ABSTRACT

The invention relates to a variable displacement pump having two connections for supplying and withdrawing a volume flow guided by said variable displacement pump. The invention is characterized in that this variable displacement pump includes an additional connection for providing and additional volume flow.

BACKGROUND

The invention relates to a variable displacement pump with two connections for supplying and withdrawing a volume flow conveyed by said variable displacement pump. The invention further relates to a method for operating such a variable displacement pump.

An electrohydraulic pressure supply is known from the German patent publication DE 199 30 648 A1 comprising an electric drive motor that is speed controllable and a variable displacement pump, with its intake volume being adjustable by an adjusting member comprising connection lines and consumer connections.

SUMMARY

The objective of the invention is to simplify the provision of volume flows that are adjustable independent from each other.

The objective is attained in a variable displacement pump with two connections for supplying and withdrawing a volume flow conveyed by the variable displacement pump such that the variable displacement pump has an additional connection for providing an additional volume flow. This way, in a simple fashion the supply of two hydraulic consumers is possible with different, variable requirements for the volume flow. The hydraulic consumers may represent for example clutch parts of a duplex clutch. The variable displacement pump is preferably connected permanently and in a driving fashion to a drive device, for example to a drive device of an internal combustion engine. The volume flows provided to the connection and the additional connection are advantageously adjustable separately from each other.

A preferred exemplary embodiment of the variable displacement pump is characterized in that the variable displacement pump can be adjusted by physical signals that are adjustable independent from each other such that the volume flows can be adjusted at two of the total of three connections independent from each other. One of the connections represents a reservoir connection, via which a hydraulic medium to be conveyed is taken in. The hydraulic medium represents for example hydraulic oil, which is also called oil, for short. The two other connections represent inputs or outputs of the variable displacement pump. The adjustment may occur two-dimensionally or three-dimensionally.

Another preferred exemplary embodiment of the variable displacement pump is characterized in that the variable displacement pump can be adjusted by physical signals that are adjustable independent from each other such that the volume flows at two of the total of three connections can be inverted with regards to their direction of flow. The inversion of the direction of flow can occur particularly advantageously without inverting the direction of rotation of the conveyance device of the variable displacement pump. The type of adjustment signal depends on the type and/or the design of the variable displacement pump.

Other preferred exemplary embodiments of the invention of the variable displacement pump are characterized in that the variable displacement pump is embodied as a cell pump or as a radial piston pump. In the cell pump and the radial piston pump the adjustment occurs preferably by displacing axes of blades towards a contour of a pump housing. Here, different directions of displacement determine the volume flow of respectively one pump outlet.

Another preferred exemplary embodiment of the variable displacement pump is characterized in that the variable displacement pump is embodied as an axial piston pump. In the axial piston pump the adjustment of the volume flow results preferably from tilting the swashplate or swash-disk, which causes an axial motion of the piston of the pump. Here, two tilting directions act upon the volume flows, which are provided at the connection and the additional connection.

In a method for operating an above-described variable displacement pump the above-stated objective is alternatively or additionally attained such that respectively one volume flow is provided to two connections. The two volume flows can be adjusted separately and independent from each other. The two volume flows that can be adjusted independent from each other may be used for operating a duplex clutch, for example.

A preferred exemplary embodiment of the method of the invention is characterized in that the volume flows provided at the two connections are adjusted independent from each other by physical signals that can be independently adjusted. The type of adjustment signals depend here on the type of variable displacement pump used.

Another preferred exemplary embodiment of the method is characterized in that at least one of the two volume flows provided at the two connections can be inverted with regards to its direction of flow. The inversion of the direction of flow occurs particularly advantageously without inverting the direction of rotation of the variable displacement pump.

Another preferred exemplary embodiment of the method is characterized in that the volume flows provided at the two connections are combined to a third volume flow. This way, the functionality of the variable displacement pump according to the invention can be further increased.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional advantages, features, and details of the invention are discernible from the following description, in which different exemplary embodiments are described in detail with reference to the drawings. Shown are:

FIG. 1 a largely simplified illustration of a variable displacement pump according to a first exemplary embodiment;

FIG. 2 a similar illustration as in FIG. 1 with additional blades displayed;

FIG. 3 a variable displacement pump of FIG. 2 with lines and arrows indicating the operation of the variable displacement pump;

FIG. 4 a perspective illustration of a variable displacement pump embodied as an axial piston pump;

FIG. 5 the variable displacement pump of FIG. 4 in a different perspective; and

FIG. 6 a simplified illustration of a variable displacement pump embodied as a radial piston pump.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 to 3 show in a simplified fashion a variable displacement pump 1 with a housing 3. A rotor 5 is rotationally driven in the housing 3. In FIG. 1 it is indicated by double arrows in the center of the rotor 5 that said rotor 5 is movable inside the housing 3 in order to adjust the conveyed volume or the intake volume of the variable displacement pump 1. Directions of adjustment are indicated in FIG. 1 by the lines 14 to 18, along which the rotor 5 can be moved inside the housing 3.

The variable displacement pump 1 comprises at the housing 3 a reservoir connection 10, a connection 11, and an additional connection 12. The reservoir connection 10 allows the supply of hydraulic media from a hydraulic medium reservoir (not shown).

The two connections 11 and 12 are advantageously adjustable independent from each other. The connection 11 is connected for example to a slave cylinder of a first clutch part of a duplex clutch. The connection 12 is then advantageously connected to a slave cylinder of a second clutch part of the duplex clutch.

The connections 10 to 12 shown represent areas in which the connections 10 to 12 are provided at the housing 3. Here, the connections 10 to 12 may be arranged in a casing area of the housing 3. However, the connections 10 to 12 may also be arranged in a facial area and/or a face of the housing 3.

It is discernible from FIG. 2 that the rotor comprises slots for the radially mobile arrangement of a total of eight blades 20. The blades 20 are arranged with their radially internal ends in the rotor slots. With their radially exterior ends the blades 20 contact an interior contour of the housing 3.

An arrow 19 in FIG. 3 indicates that the rotor 5 is driven in the clockwise direction. During operation the rotor 5 rotates with the blades 20 in a housing 3. An adjustment of the volume flows, provided by the variable displacement pump during operation, occurs by displacing the rotor 5 in reference to the housing 3.

The displacements indicated by the double arrows in the center of the rotor 5 shown in FIGS. 1 and 2 may be initiated from the outside at the rotor 5 or the housing 3. In a rotationally driven rotor 5 it may be beneficial to implement the relative motion for adjusting the volume flows provided by the adjustment pump 1 by displacements at the housing 3.

The drive of the rotor 5 may for example occur by a fixed coupling to a drive train of a motor vehicle. Although the displacement for adjusting the volume flows can occur both by the housing 3 as well as the rotor 5, in the following the adjustment is explained based on an adjustment of the rotor 5.

Dot-dash lines 21 and 22 in FIG. 3 indicated axes of motion along which the rotor 5 can be moved in order to adjust the volume flows provided at the connections 11 and 12. Arrows 23 and 24 represent indicators for the direction of the pump for a first consumer, for example a first clutch part of a duplex clutch. Here, the dot-dash line 21 represents a neutral line for the first consumer. The arrows 25 and 26 are indicators for the direction of the pump for a second consumer, for example for a second clutch part of the duplex clutch. Here, the dot-dash line 22 represents a neutral line for the second consumer.

When the rotor 5 is displaced along the dot-dash line 21 the volume flow of the first consumer remains zero. Similarly, the volume flow of the second consumer remains zero when the rotor 5 is displaced along the dot-dash line 22.

When the rotor 5 is precisely in the middle, as shown in FIG. 3, it is arranged on both neutral lines 21, 22. Then the volume flows conveyed by the variable displacement pump 1, for example the volume flows provided at the two connections 11 and 12, are zero independent from a speed of the rotor 5.

When the rotor 5 is moved from the neutral line 21 upwards towards the left, the hydraulic medium or fluid is suctioned at the connection 11 in the direction towards the variable displacement pump as indicated by the motion arrow 23. Additionally, at the same direction of rotation during a motion of the rotor 5 towards the right bottom, here fluid or hydraulic medium is pushed out of the variable displacement pump at the connection 11 as indicated by the motion arrow 24.

If the rotor 5 is moved from the neutral line 22 upwards towards the right, the fluid is suctioned at the connection 12 in the direction towards the variable displacement pump, as indicated by the motion arrow 25. Additionally, at an identical direction of rotation during a motion of the rotor 5 downwards towards the left fluid is pushed out of the variable displacement pump at the connection 12, as indicated by the motion arrow 26.

FIG. 4 shows a variable displacement pump 31 in various illustrations in a perspective fashion. The variable displacement pump 31 is embodied as an axial piston pump and can be similarly adjusted like the above-described variable displacement pump 1.

The axial piston pump 31 comprises a housing 33 with a disk 34. A revolver 35 is equivalent to the rotor (5 in FIG. 1) and can be driven in a rotary fashion. Pistons 36 are guided in a movable fashion in an axial direction back and forth in the revolver 35.

The pistons 36 rest via sliding shoes 37 on a swashplate 38. Levers 39 symbolizing the axes are provided at the swashplate 38 in order to allow pivoting the swashplate 38 for adjusting the conveyed volume or the intake volume of the variable displacement pump.

A reservoir connection 40 is provided in the disk 34. Furthermore, a connection 41 and an additional connection 42 are provided in the disk 34.

Compared to the above-described variable displacement pump 1, the volume flows of the variable displacement pump 31 provided at the connections 41 and 42 are adjusted via an incline of the swashplate 38 instead of a displacement. During operation of the variable displacement pump 31 the revolver 35 rotates in reference to the disk 34 with the connections 40 to 42. Here, the revolver 35 also rotates in reference to the swashplate 38, with the rotating revolver 35 entraining the piston 36.

The drive of the revolver 35 is not shown and can occur in various fashions. The drive of the revolver 35 can occur via a shaft, for example, extending through the swashplate 38 or through the disk 34. Alternatively the piston 35 can be driven directly via gears embodied on the revolver 35 itself.

The incline of the swashplate 38 can be adjusted in a three-dimensional fashion. The control during the adjustment of the variable displacement pump 31 occurs similar to the above-described adjustment of the cell pump 1. Contrary to the cell pump 1 the axial piston pump 31 is not deflected by tilting.

The adjusting or setting of the variable displacement pump 31 occurs with a separate mechanical component, with its connection here being shown only schematically in the form of levers 39. The variable displacement pump 31 shown in FIGS. 4 and 5 comprises three pistons 36 in the revolver 35. Contrary to the version shown, preferably more than three pistons 36 are provided in the revolver 35, for example five or six pistons 36, guided back and forth in an axially movable fashion.

FIG. 5 shows the axial piston pump 31 from a slightly modified perspective with the disk 34 being lifted off. Due to the fact that the disk 34 comprises the connections 40 to 42 the disk 34 is also called a connection disk. The support 45 of the swashplate 38 occurs via a spherical geometry as shown in FIG. 5 as an example.

FIG. 6 shows a variable displacement pump 51 embodied as a radial piston pump. The radial piston pump 51 comprises a housing 53 in which a rotor 55 is driven rotationally in the clockwise direction, as indicated by an arrow in the center of the rotor 55. In the rotor 55, radially at the outside a total of eight pistons 56 are guided movable back and forth.

The radially aligned pistons 56 are each arranged with their radially interior end in the rotor 55. With their respectively radial exterior end the pistons 56 contact an internal contour of the housing 53, perhaps with sliding shoes interposed. In a similar fashion as the cell pump 1 shown in FIGS. 1 to 3, the housing 53 comprises a reservoir connection 60, a connection 61, and an additional connection 62.

During operation of the radial piston pump 51 the pistons 56 are pushed radially inwardly. The adjustment of the volume flows provided at the connections 61 and 62 occurs similar to the cell pump 1 shown in FIGS. 1 to 3 via a translation between the housing 53 and the rotor 55.

LIST OF REFERENCE CHARACTERS

-   1 variable displacement pump -   3 housing -   5 rotor -   10 reservoir connection -   11 connection -   12 additional connection -   14 line -   15 line -   16 line -   17 line -   19 arrow -   20 blade -   21 dot-dash line -   22 dot-dash line -   23 arrow -   24 arrow -   25 arrow -   26 arrow -   31 variable displacement pump -   33 housing -   34 disk -   35 revolver -   36 piston -   37 sliding shoe -   38 swashplate -   39 lever -   40 reservoir connection -   41 connection -   42 additional connection -   45 support -   51 variable displacement pump -   53 housing -   55 rotor -   56 piston -   60 reservoir connection -   61 connection -   62 additional connection 

1. A variable displacement pump, comprising two connections for supplying and withdrawing a volume flow conveyed by the variable displacement pump, and an additional connection for providing an additional volume flow, forming a total of three connections.
 2. The variable displacement pump according to claim 1, wherein the variable displacement pump is adjustable by physical signals that are adjustable independent from each other such that the volume flows at two of the total of three connections are adjustable independent from each other.
 3. The variable displacement pump according to claim 1, wherein the variable displacement pump is adjustable by physical signals adjustable independent from each other such that the volume flows are inverted with regards to a direction of flow at two of the total of three connections.
 4. The variable displacement pump according to claim 1, wherein the variable displacement pump is a cell pump.
 5. The variable displacement pump according to claim 1, wherein the variable displacement pump is a radial piston pump.
 6. The variable displacement pump according to claim 1, wherein the variable displacement pump is an axial piston pump.
 7. The method for operating a variable displacement pump according to claim 1, wherein respective ones of the volume flows provided at respective ones of two of the connections.
 8. The method according to claim 7, wherein the volume flows provided at the two connections are adjustable independent from each other by independently adjustable physical signals.
 9. The method according to claim 7, wherein at least one of the volume flows provided at the two connections is inverted with regards to a direction of flow.
 10. The method according to claim 7, wherein the volume flows provided at the two connections are combined to form a third volume flow. 